Will these work with my current wheels?

These are M12 x 1.5 — the most common thread pitch. Check your existing lug nut thread pitch before ordering to confirm compatibility.

Can I clean the gun metal finish, or does it need special care?

Wash them with soap and water like any wheel hardware. The aluminum finish will patina over time if exposed to moisture — some drivers embrace the look, others apply clear coat for protection.

Do I get all 20 nuts in one set, or is this per-wheel?

This is a 20-piece set — enough for all five wheels on most vehicles with spares included.